Patent Document 1 discloses a conventional stent. This stent includes a stent body and a valving element and is cylindrical in shape. The stent body is formed into a mesh pattern and has one insertion hole through which a catheter is insertable. The valving element is provided to cover the insertion hole of the stent body. The valving element has a flange-shaped base bonded to an outer peripheral edge of the insertion hole of the stent body and a projection which projects outside the stent body from the base. The projection comprises an elastic membrane and has a top formed with a linear shaped slit.
This stent is indwelled in a blood vessel so that the valving element is located in proximity to an opening of an aneurysm and so that the projection projects toward an inside of the aneurysm. A distal end of the catheter expands the slit from inside, projecting to place an embolic material into the aneurysm. Subsequently, when the catheter is pulled out, the slit is closed to adhere tightly. As a result, this stent can suppress outflow into the blood vessel of the embolic material placed in the aneurysm.